Rectifying system



Sept. 16, 1930.

c. KRAMER REGTIFYING SYSTEM Filed March 17, 1927 Inventor? Christian Krimeml Patented Sept. 16, 1930 :11.

UNITED STATES CHRISTIAN KRAME or BERLIN, GERMANYQAssI RQR "r 0 GENERAL ELRoTR IoooM I I PANY, A CORPORATION on NEW YORK;

REc'rIrYmef'sYsrn Application filed March 17, 1927, Serial No. 176,242, and in G rmany Nb einter "11. 1926." g y My invention relates torectifying systems wherein current is transmitted between the anodes and cathode of a mercury rectifier or the like, and has for its principal object the provision of an improved arrangement of the anode leads whereby the tendency of the current to concentrate at the edge of the cathode is avoided.

My invention will be better understood .from the following description when considered in connection with the accompanying drawings and its scope will be pointed out in the appended claims.

Referring to the drawings, Fig. 1 illustrates certain details in the operation of a mercury arc rectifier; Fig. 2 illustrates a mercury rectifier wherein my invention has been embodied; and Fig. 3 illustrates a further embodiment of my invention.

In the operation of mercury arc rectifiers, it is observed that the point at which the arc strikes the mercury, the so-called cathode spot, has the tendency with increasing current strength to travel to the wall of the cathode casing, to settle there and to cause damage. WVith a large current strength this tendency is so pronounced that even internal structures of insulating materials, which are intended to keep the are away from the edge of the cathode vessel, are destroyed. The travelling action of the cathode spot is intended to be illustrated with the aid of Fig. 1, which represents diagrammatically a large rectifier of the usual type of construction. 7

g is the casing, a are the anodes, which are fed by the transformer (Z, the centre point e of which forms the negative pole. To the lower part of the casing there is fixed, insulated by the insulating ring z', an iron vessel 7;,

which forms the cathode and is about half filled with mercury. The current outlet is at the bottom of the vessel. The unstable behaviour of the arc is indicated by the current lines m, n, 37. Let it be assumed that the current is at first travelling according to the line m, exactly towards the centre of the mercury pool. The are is now pushed away from the centre by the vaporizing mercury,

and the current line assumes a loop form n which tends to extend. The current line consequently travels towards the side, theloop 7 New inorderto keep the'arb away-fromthe casing wall as far as possible and force it to keep tothe centre of the mercury pool, according to the invention, there are provided for taking off the current several connections which are arranged on the edge of the cathode vessel, preferably above the mercury pool.

In Figs. 2 and 3 two constructional examples of an arrangement in accordance with the invention are represented.

As may be seen from the figures, the current collectors r are arranged on the upper part of the cathode vessel. It is expedient to distribute them at uniform intervals round the cathodevessel. The course of the current is indicated by the arrows. I

If in such a rectifier, the arc has a tendency to travel towards the Wall of the vessel, it is driven back into the centre by the magnetic field surrounding the leads through which current is transmitted to the collectors 1'.

In the arrangement according to Fig. 3 the upper part of the cathode vessel forms a funnel which is immersed in the mercury. It is expedient to coat the upper surface of this funnel with a non-conducting enamel, and likewise the inner wall of the cathode vessel. The current takes the course indicated by the arrows. It is advantageous to provide still further protective devices, e. g. aninsertion 25 of insulating material, which protects the insulating ring '5 from the radiating heat of the arc. The funnel-shaped part of the cathode is appropriately provided with a few holes or incisions in order to facilitate the circulation of the mercury.

What I claim as new and desire to secure by Letters Patent of the United States, is

1. The combination of a rectifier comprising a cathode vessel provided with a funnel shaped flange fixed to its inner surface and a plurality of cathode leads connected to said vessel at different points around its upper edge.

2. The combination of a rectifier comprising a cathode vessel provided with a funnelshaped flange fixed to and extending downwardly from the upper part of its inner surface, a vaporizable cathode located in the bottom of said vessel and arranged to engage the lower edge of said flange, and a plural ity of cathode leads connected to said vessel at different points around its upper exterior surface; I

3. The combination of a rectifier comprising a conductive cathode vessel having a mercury pool therein, an anode and a plurality of cathode leadseach connected to said cathode vessel adjacent the upper :edge thereof and spaced substantially uniformly thereabout to prevent the are between cathode and anode from travelling toward the wall of said vessel and to malntain said are substantially at the center of the surface of said mercury pool. In witness whereof, I have hereto set my hand this 25th day of February; 1927.

CHRISTIAN KRAMER. 

